U.S. patent application number 09/778043 was filed with the patent office on 2002-02-07 for filtering unsaturated hydrocarbons using intermetallic nano-clusters.
Invention is credited to Jena, Purusottam, Koller, Kent B., Lilly, A. Clifton JR., Paine, John B. III, Rao, Bijan K..
Application Number | 20020014453 09/778043 |
Document ID | / |
Family ID | 26876558 |
Filed Date | 2002-02-07 |
United States Patent
Application |
20020014453 |
Kind Code |
A1 |
Lilly, A. Clifton JR. ; et
al. |
February 7, 2002 |
Filtering unsaturated hydrocarbons using intermetallic
nano-clusters
Abstract
A filter such as a cigarette filter having a metal reagent which
selectively binds with a gaseous component of a gas stream such as
tobacco smoke. The metal reagent comprises nanometer or micrometer
size clusters of a transition metal or alloy containing a
transition metal. The transition metal can be incorporated in an
intermetallic compound such as titanium aluminide or iron
aluminide. The metal clusters can be incorporated in or on a
support material such as silica gel, porous carbon or a zeolite.
The metal reagent can remove the gaseous component by selectively
binding to unsaturated hydrocarbons such as 1,3-butadiene. The
binding can occur by insertion of a metal atom of the metal reagent
into a C--H bond or a C--C bond of the gaseous component.
Inventors: |
Lilly, A. Clifton JR.;
(Chesterfield, VA) ; Koller, Kent B.;
(Chesterfield, VA) ; Paine, John B. III;
(Midlothian, VA) ; Jena, Purusottam; (Richmond,
VA) ; Rao, Bijan K.; (Richmond, VA) |
Correspondence
Address: |
Peter K. Skiff
BURNS, DOANE, SWECKER & MATHIS, L.L.P.
P.O. Box 1404
Alexandria
VA
22313-1404
US
|
Family ID: |
26876558 |
Appl. No.: |
09/778043 |
Filed: |
February 7, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60180681 |
Feb 7, 2000 |
|
|
|
Current U.S.
Class: |
210/504 ;
210/505 |
Current CPC
Class: |
A24B 15/286 20130101;
B01D 39/02 20130101; A24D 3/16 20130101 |
Class at
Publication: |
210/504 ;
210/505 |
International
Class: |
B01D 039/02; B01D
039/06 |
Claims
1. A filter comprising a metal reagent which binds with a gaseous
component of a gas stream to remove said gaseous component from
said gas stream.
2. The filter according to claim 1, wherein the filter comprises a
cigarette filter attached to a tobacco rod by tipping paper or the
metal reagent is incorporated in one or more cigarette filter parts
selected from the group consisting of tipping paper, shaped paper
insert, a plug, a space, or a free-flow sleeve.
3. The filter according to claim 1, wherein the metal reagent
selectively binds to unsaturated hydrocarbons in the gas
stream.
4. The filter according to claim 1, wherein the metal reagent
comprises nanometer or micrometer size clusters of a transition
metal or alloy containing a transition metal or a transitional
metal salt.
5. The filter according to claim 1, wherein the gaseous component
to be removed from said gas stream is 1,3-butadiene, isoprene
and/or toluene.
6. The filter according to claim 4, wherein said metal reagent is
incorporated in cigarette filter paper located within a free-flow
filter, the filter paper optionally having a three-dimensional
shape and/or the filter paper being a liner on the interior of a
hollow tubular element.
7. The filter according to claim 1, wherein said metal reagent is
incorporated with cellulose acetate fibers and/or polypropylene
fibers forming a plug or a free-flow filter element.
8. The filter according to claim 4, wherein said metal reagent is
incorporated in or on a support material.
9. The filter according to claim 8, wherein said support material
comprises silica gel, porous carbon or a zeolite.
10. The filter according to claim 4, wherein said transition metal
includes iron and/or titanium.
11. The filter according to claim 1, wherein said metal reagent
comprises nanometer or micrometer size clusters of an iron
aluminide or a titanium alumlnide.
12. The filter according to claim 1, wherein a metal atom of the
metal reagent binds to a C--H bond and/or a C--C bond of the
gaseous component.
13. A method of manufacturing a filter which is useful for removing
a gaseous component of a gas stream, comprising steps of:
incorporating a metal reagent in a filter, the metal reagent being
effective to bind with a gaseous component of a gas stream
sufficiently to selectively remove the gaseous component from the
gas stream.
14. The method according to claim 13, further comprising attaching
the filter to a tobacco rod with tipping paper or the metal reagent
is incorporated in one or more cigarette filter parts selected from
the group consisting of tipping paper, shaped paper insert, a plug,
a space, or a free-flow sleeve.
15. The method according to claim 14, further comprising a step of
attaching the filter paper within a free-flow filter of a cigarette
such as by forming said filter paper into a three-dimensional shape
or attaching said filter paper as a liner on the interior of a
hollow tubular element or combining said metal reagent with fibers
and forming a filter element from said metal reagent and fibers or
combining said metal reagent with cellulose and/or polypropylene
fibers and forming a plug or free-flow filter element or
incorporating said metal reagent in a cavity of said filter.
16. The method according to claim 13, wherein the metal reagent is
effective for removing unsaturated hydrocarbons including
1,3-butadiene, isoprene and/or toluene from the gas stream.
17. The method according to claim 13, wherein the metal reagent
comprises nanometer or micrometer size clusters of a transition
metal or alloy containing a transition metal or a transitional
metal salt.
18. The method according to claim 17, further comprising a step of
loading said metal reagent in or on a support material forming a
filter element of the filter.
19. The method according to claim 18, wherein the support material
comprises silica gel, porous carbon or a zeolite.
20. A method of removing a gaseous component from a gas stream,
comprising passing the gas stream in contact with a filter
comprising a metal reagent which binds with a gaseous component of
the gas stream and removes said gaseous component from the gas
stream.
21. The method according to claim 20, further comprising steps of
forming the gas stream by burning tobacco and directing tobacco
smoke through the filter such that the component of the gas stream
to be removed is brought into contact with the metal reagent and
prevented from reentering the gas stream.
22. The method according to claim 21, wherein the metal reagent is
incorporated in one or more cigarette filter parts selected from
the group consisting of filter paper, tipping paper, shaped paper
insert, a plug, a space, or a free-flow sleeve, the tobacco smoke
being passed through the one or more filter parts.
23. The method according to claim 20, wherein the metal reagent is
effective to selectively remove unsaturated hydrocarbons present in
the gas stream.
24. The method according to claim 20, wherein the metal reagent
comprises nanometer or micrometer size clusters of a transition
metal or alloy containing a transition metal or a transitional
metal salt.
25. The method according to claim 20, wherein the filter removes
1,3-butadiene, isoprene and/or toluene from the gas stream.
26. The method according to claim 20, wherein the metal reagent is
incorporated in or on a support material selected from the group
consisting of silica gel, porous carbon or a zeolite.
27. The method according to claim 26, wherein said silica gel has
an average particle diameter of at least 10 .mu.m or said silica
gel is in the form of particles having a mesh size of at least 60
and the gas stream is passed through a mass of particles of said
silica gel.
28. The method according to claim 26, wherein said silica gel is
incorporated with cellulose acetate fibers and/or polypropylene
fibers and the gas stream is a smoke stream from a burning
cigarette.
29. The method according to claim 20, wherein a metal atom of the
metal reagent binds to a C--H bond and/or a C--C bond of the
gaseous component.
30. The filter according to claim 1, wherein the metal reagent is a
non-oxide metal reagent or a crystalline metal reagent.
31. The method according to claim 13, wherein the metal reagent is
a non-oxide metal reagent or a crystalline metal reagent.
Description
[0001] The invention relates to filtering of unsaturated
hydrocarbons from mainstream cigarette smoke using intermetallic
nano-clusters. The nano-clusters can be incorporated in cigarette
filter elements in a manner which selectively removes gaseous
components such as 1,3-butadiene, isoprene, toluene and the like
from mainstream smoke.
[0002] Fresh activated carbon can be used to reduce the level of
1,3-butadiene in mainstream cigarette smoke. However, because
activated carbon is a broad base physical adsorbent of gaseous
compounds and removes a large number of volatile and gas-phase
compounds from cigarette smoke, the result can produce undesired
effects on the flavor of the tobacco smoke. Selective filtration,
on the other hand, has the advantage of removing targeted gaseous
compounds while minimizing the effect on flavor of the tobacco
smoke.
[0003] According to the invention, small (nanometer or micrometer
size) metal or metal alloy clusters can be incorporated in or on a
support media (e.g., silica gel, porous carbon, zeolites, etc.) and
the resulting filter material can be used to selectively bind to
unsaturated hydrocarbons present in cigarette smoke. In a preferred
embodiment, transition metals and metal alloys incorporated into
the clusters can be used to remove gaseous components such as
1,3-butadiene from mainstream cigarette smoke as it passes through
a filter containing the supported reactive metal clusters. The
transition metals can include iron and titanium and alloys
containing such elements such as iron alloys, titanium alloys,
intermetallic compounds such as iron aluminide or titanium
aluminide or transition metal salts (e.g., Cu, Fe, Zn, Al, Ce, V
sulfates and/or phosphates) on high surface area support
materials.
[0004] Using state-of-the-art theoretical techniques based on
density functional theory and generalized gradient approximation
for exchange and correlation potential, calculations of the binding
energies of trans- and cis-form of butadiene to transition metal
atom (Fe) as well as dimers (Fe.sub.2, FeAl, and Al.sub.2) were
carried out. The objective of the study was to understand if (1)
butadiene binds to these species and, if so, how the binding varies
from one atom to another, (2) if one form of butadiene binds more
strongly than the other, (3) where do the metal atoms insert and
(4) if the structure of butadiene undergoes geometrical
transformation as it binds to metal atoms. The study was carried
out to see if suitable traps can be found for this organic molecule
and to suggest experiments to prove the theoretical
predictions.
(1) Geometry of cis- and trans-butadiene as they interact with
metal atoms and dimers
[0005] In FIG. 1(a) the trans form of butadiene is given. It is a
planar molecule. An Fe atom inserts into the C--H bond and gains an
energy of 0.37 eV (see Table 1) over an isolated trans-butadiene
and Fe atom. While interacting with the cis-form (FIG. 2), the Fe
atom, on the other hand, attaches to the C--C double bond and the
structure becomes three-dimensional. Energetically, the
Fe-butadiene complex in the cis-form is more stable than the
trans-form by 0.78 eV. This is particularly interesting as the
trans- and cis-forms of butadiene are energetically nearly
degenerate. Addition of Fe does seem to break this degeneracy.
[0006] Fe.sub.2 does not bind to the trans- or cis-form of
butadiene (FIG. 1(c)) as energetically this is higher than
dissociated Fe.sub.2 and butadiene. FeAl and Al.sub.2 dimers, on
the other hand, bind strongly to both the trans- and cis-forms of
butadiene. While the bond between Fe and Al remains intact (see
FIGS. 1(d) and 2(c)), that between Al and Al breaks (see FIGS. 1(e)
and 2(d)). This is because the Fe--Al bond is stronger than the
Al--Al bond. Nevertheless, a binding energy in excess of 1 eV
between a metal dimer and butadiene is sufficient. The C--C and
C--H bonds in butadiene do not change appreciably as metal atoms
are bound to the molecule.
(2) Binding of metal atoms to C.sub.2 and C--H dimers
[0007] From the above discussion it is apparent that a metal atom
either inserts into the C--H bond or attaches to a C--C bond in
butadiene. As calculations presented in FIG. 1 and FIG. 2 and Table
1 are very complex and costly, the systematics of transition metal
binding to CH and C.sub.2 molecules was studied to see which atoms
can possibly bond more strongly to butadiene than Fe. The
corresponding energies are given in Table 2. The data indicates
that Sc, Ti, V, Co, and Ni are better candidates than Fe whether
they prefer to insert into the CH bond or attach to C-C bond.
Calculations of Sc, Ti, V, Co, and Ni interacting with the complete
butadiene molecule can be carried out to prove this hypothesis.
Experimental studies of transition metal atoms and Al reacting with
butadiene in the gas phase can also be carried out.
1 TABLE 1 Binding Energy (eV) System Trans (FIG. 1) Cis (FIG. 2)
C.sub.4H.sub.6 43.98 43.82 C.sub.4H.sub.6Fe 0.37 1.15
C.sub.4H.sub.6Fe.sub.2 -- -- C.sub.4H.sub.6FeAl 1.35 1.76
C.sub.4H.sub.6Al.sub.2 2.22 2.03 E.sub.b(C.sub.4H.sub.6) =
E(C.sub.4H.sub.6)--4E(C)--6E(H- ) E.sub.b(C.sub.4H.sub.6Fe) =
E(C.sub.4H.sub.6Fe)--E(C.sub.4H.sub- .6)--E(Fe)
E.sub.b(C.sub.4H.sub.6FeAl) = E(C.sub.4H.sub.6FeAl)--E-
(C.sub.4H.sub.6)--E(FeAl) E.sub.b(C.sub.4H.sub.6Al.sub.2) =
E(C.sub.4H.sub.6Al.sub.2)--E(C.sub.4H.sub.6)--E(Al.sub.2)
E.sub.b(Al.sub.2) = E(Al.sub.2)--2E(Al) = 1.76 eV E.sub.b(FeAl) =
E(FeAl)--E(Fe)--E(Al) = 2.53 eV E = total energy, kE.sub.b =
binding energy
[0008]
2TABLE 2 Energetics of M-C.sub.2 and M-CH (M = Sc . . . Ni) in eV M
E.sub.b(MC.sub.2) E.sub.b(MCH) Sc 6.76 9.02 Ti 6.95 6.21 V 7.28
4.95 Cr 4.37 4.08 Mn 5.03 3.61 Fe 4.86 4.68 Co 6.16 5.45 Ni 6.74
5.79 E.sub.b(MC.sub.2) = E(MC.sub.2)--E(M)--E(C.sub.2) E.sub.b(MCH)
= E(MCH)--E(M)--E(CH)
[0009] Clusters of nanosize intermetallic powders such as
Fe.sub.3Al, FeAl, TiAl, NiAl and Ni.sub.3Al can be obtained by
melting and atomization techniques. They can be processed by laser
evaporation, and or chemical decomposition techniques. The powders
can be produced in inert atmospheres such as argon or helium, or by
bleeding a certain amount of oxygen, nitrogen, or ammonia to alter
the surface property of the powders. The sizes of the particles may
be altered by the residence time of the laser pulse, cooling time,
temperature, etc. For instance, it is possible to synthesize
nanoparticles of controlled size and composition using pulsed laser
vaporization with controlled condensation (LVCC) in a diffusion
cloud chamber under well-defined conditions of temperature and
pressure.
[0010] While the invention has been described in detail with
reference to specific embodiments thereof, it will be apparent to
those skilled in the art that various changes and modifications can
be made, and equivalents employed, without departing from the scope
of the appended claims.
* * * * *